Re: Build failed in Jenkins: osv-build #1253

2017-07-17 Thread Avi Kivity 



On 07/17/2017 03:34 PM, Nadav Har'El wrote:


On Mon, Jul 17, 2017 at 3:29 PM, Avi Kivity > wrote:




On 07/17/2017 10:10 AM, Nadav Har'El wrote:

Oops, this is bad, and unfortunately I committed too many patches
yesterday to understand which one brought this bug...



On Sun, Jul 16, 2017 at 7:57 PM, mailto:jenk...@scylladb.com>> wrote:

  TEST tst-elf-permissions.so OSv v0.24-399-ge6fadac
eth0: 192.168.122.15
Assertion failed: (phdr.p_flags & (PF_R | PF_W | PF_X)) ==
PF_R (core/elf.cc: fix_permissions: 475)


We've seen Jenkins doing two runs and both of them failed at
exactly the same place. Moreover, on my Fedora 25 installation, I
ran this test 1000 times, and it didn't fail once

Note how the failure is while *loading* the test object, not even
when running it, where we discover that the GNU_RELRO section is
not marked read-only. This can either be memory corruption (oops)
or a linker bug (this particular test does funky monkey-business
on the linker).

It turns out to be the latter: The test fails if the "gold"
linker is used to build it. If I add "-fuse-ld=gold" in COMMON in
modules/tests/Makefile, running this test fails with the exact
same assertion, and it's clear why:

$ readelf -a build/release/tests/tst-elf-permissions.so
Program Headers:
  Type   Offset VirtAddr   PhysAddr
 FileSiz MemSiz  Flags  Align
...
  GNU_RELRO  0x1da0 0x2da0
0x2da0
 0x0260 0x0260  RW 8

Note how GNU_RELRO is marked read-write, but it should have been
read-only.

I am guessing that recently, our Jenkins machine was modified to
change the default BFD linker to the GOLD one. Is this possible?


It is, and I did that to speed up Scylla links.


Ok, thanks.

If scylla is known to work well with gold, would it not make sense to 
just add "-fuse-ld=bfd" in its compilation line instead of assume that 
everyone compiling it remembers to switch the default?




It does make sense.

Clang doesn't have -fuse-ld, so we have to detect it at configure time.

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Re: Build failed in Jenkins: osv-build #1253

2017-07-17 Thread Nadav Har'El 
On Mon, Jul 17, 2017 at 3:29 PM, Avi Kivity  wrote:

>
>
> On 07/17/2017 10:10 AM, Nadav Har'El wrote:
>
> Oops, this is bad, and unfortunately I committed too many patches
> yesterday to understand which one brought this bug...
>
>
>
> On Sun, Jul 16, 2017 at 7:57 PM,  wrote:
>
>>   TEST tst-elf-permissions.so OSv v0.24-399-ge6fadac
>> eth0: 192.168.122.15
>> Assertion failed: (phdr.p_flags & (PF_R | PF_W | PF_X)) == PF_R
>> (core/elf.cc: fix_permissions: 475)
>>
>>
> We've seen Jenkins doing two runs and both of them failed at exactly the
> same place. Moreover, on my Fedora 25 installation, I ran this test 1000
> times, and it didn't fail once
>
> Note how the failure is while *loading* the test object, not even when
> running it, where we discover that the GNU_RELRO section is not marked
> read-only. This can either be memory corruption (oops) or a linker bug
> (this particular test does funky monkey-business on the linker).
>
> It turns out to be the latter: The test fails if the "gold" linker is used
> to build it. If I add "-fuse-ld=gold" in COMMON in modules/tests/Makefile,
> running this test fails with the exact same assertion, and it's clear why:
>
> $ readelf -a build/release/tests/tst-elf-permissions.so
> Program Headers:
>   Type   Offset VirtAddr   PhysAddr
>  FileSizMemSiz  Flags  Align
> ...
>   GNU_RELRO  0x1da0 0x2da0 0x2da0
>  0x0260 0x0260  RW 8
>
> Note how GNU_RELRO is marked read-write, but it should have been read-only.
>
> I am guessing that recently, our Jenkins machine was modified to change
> the default BFD linker to the GOLD one. Is this possible?
>
>
> It is, and I did that to speed up Scylla links.
>

Ok, thanks.

If scylla is known to work well with gold, would it not make sense to just
add "-fuse-ld=bfd" in its compilation line instead of assume that everyone
compiling it remembers to switch the default?

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Re: Build failed in Jenkins: osv-build #1253

2017-07-17 Thread Avi Kivity 



On 07/17/2017 10:10 AM, Nadav Har'El wrote:
Oops, this is bad, and unfortunately I committed too many patches 
yesterday to understand which one brought this bug...




On Sun, Jul 16, 2017 at 7:57 PM, > wrote:


  TEST tst-elf-permissions.so OSv v0.24-399-ge6fadac
eth0: 192.168.122.15
Assertion failed: (phdr.p_flags & (PF_R | PF_W | PF_X)) == PF_R
(core/elf.cc: fix_permissions: 475)


We've seen Jenkins doing two runs and both of them failed at exactly 
the same place. Moreover, on my Fedora 25 installation, I ran this 
test 1000 times, and it didn't fail once


Note how the failure is while *loading* the test object, not even when 
running it, where we discover that the GNU_RELRO section is not marked 
read-only. This can either be memory corruption (oops) or a linker bug 
(this particular test does funky monkey-business on the linker).


It turns out to be the latter: The test fails if the "gold" linker is 
used to build it. If I add "-fuse-ld=gold" in COMMON in 
modules/tests/Makefile, running this test fails with the exact same 
assertion, and it's clear why:


$ readelf -a build/release/tests/tst-elf-permissions.so
Program Headers:
  Type   Offset VirtAddr PhysAddr
 FileSizMemSiz Flags  Align
...
  GNU_RELRO  0x1da0 0x2da0 0x2da0
 0x0260 0x0260 RW 8

Note how GNU_RELRO is marked read-write, but it should have been 
read-only.


I am guessing that recently, our Jenkins machine was modified to 
change the default BFD linker to the GOLD one. Is this possible?


It is, and I did that to speed up Scylla links.



An easy fix would be to add -fuse-ld=bfd. I'm trying to think if 
that's the right fix, though.


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Re: Build failed in Jenkins: osv-build #1253

2017-07-17 Thread Nadav Har'El 
Oops, this is bad, and unfortunately I committed too many patches yesterday
to understand which one brought this bug...



On Sun, Jul 16, 2017 at 7:57 PM,  wrote:

>   TEST tst-elf-permissions.so OSv v0.24-399-ge6fadac
> eth0: 192.168.122.15
> Assertion failed: (phdr.p_flags & (PF_R | PF_W | PF_X)) == PF_R
> (core/elf.cc: fix_permissions: 475)
>
>
We've seen Jenkins doing two runs and both of them failed at exactly the
same place. Moreover, on my Fedora 25 installation, I ran this test 1000
times, and it didn't fail once

Note how the failure is while *loading* the test object, not even when
running it, where we discover that the GNU_RELRO section is not marked
read-only. This can either be memory corruption (oops) or a linker bug
(this particular test does funky monkey-business on the linker).

It turns out to be the latter: The test fails if the "gold" linker is used
to build it. If I add "-fuse-ld=gold" in COMMON in modules/tests/Makefile,
running this test fails with the exact same assertion, and it's clear why:

$ readelf -a build/release/tests/tst-elf-permissions.so
Program Headers:
  Type   Offset VirtAddr   PhysAddr
 FileSizMemSiz  Flags  Align
...
  GNU_RELRO  0x1da0 0x2da0 0x2da0
 0x0260 0x0260  RW 8

Note how GNU_RELRO is marked read-write, but it should have been read-only.

I am guessing that recently, our Jenkins machine was modified to change the
default BFD linker to the GOLD one. Is this possible?

An easy fix would be to add -fuse-ld=bfd. I'm trying to think if that's the
right fix, though.

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